Lubricating oil composition containing 3:2alpha-glycol borate compounds



Patented June 20, 19 61 United States Patent ce 1 2,989,467 vLUBRICATING OIL COMPOSITION CONTAINING 3:2a-GLYCOL BORATE COMPOUNDSSamuel M. Darling, Lyndhurst, and Chien-Wei Liao,

Cleveland, Ohio, assignors to The Standard Oil Company, Cleveland, Ohio,a corporation of Ohio No Drawing. Filed Dec. 30, 1957, Ser. No. 705,8164Claims. (Cl. 252-496) boric acid in the ratio of three moles of thediol to two moles of the boric acid.

One of the most serious problems encountered in the operation ofinternal combustion engines is the deposits which form progressivelyand'accumulate on the surfaces within the combustion zone, on thecylinder head, piston top, sparkplug and the intake and exhaust valves.These deposits are made more stubborn by the tetraethyl lead present inmost gasoline fuels, because this not only contributes to the depositbut it also converts it from an essentially carbonaceous deposit to onecomprising appreciable quantities of lead and lead compounds mixedtherewith, such as lead sulfate, and lead oxide. The carbonaceousdeposits act as a cementing agent for the lead deposits, and the leaddeposits are more difiicult to remove than the carbon deposits. Thus, adeposit of this sort is more tenacious and troublesome than a purelycarbonaceous deposit.

The nature of the lead-carbonaceous deposits is such that they are quitedifiicult to remove, once they have been built up. They are not attackedby the scavenging agents which are included in the fuel with thetetraethyl lead. Despite the fact that the amount of the depositseventually levels off, after which there is no appreciable furtherincrease, the presence of the built-up deposits interferes considerablywith the operation of the engine, and it would be desirable both toprevent formation of deposits and to remove them after they have beenformed. The disadvantageous effects of these deposits are well discussedin U.S. Patent No. 2,741,548to Samuel M. Darling, Philip S. Fay andLorraine S. Szabo.

It has been proposed to attack such deposits by incorporating in theliquid leaded motor fuel an organic boron compound which is soluble inthe fuel. The boron compound is thought to modify the action of the fuelin the engine, and to react with the deposits so that the adverseeffects due to the deposits are eliminated or markedly reduced.

It is known that the carbonaceous components of the deposits in theengine are built up not only from the gasoline but also from the oil,which enters the combustion system from the crankcase in various ways.This oil is in the liquid phase in the combustion zone of the engine,whereas the gasoline, of course, is in the vapor phase. However, it isessential that the boron compound be soluble in the medium in which itis introduced into the engine. For use in lubricating oil, thesolubility must be quite high, relative to that in gasoline, becausemore additive is needed in the lubricating oil to obtain an effect.Moreover, the stability of the boron compound against hydrolysis must behigh, in view of the'larger amounts of compound present, and thehydrolysis products must be soluble in the oil as well, since insolubleboron deposits in the crankcase and lubricated parts of the engine mightbe harmful and certainly would be difli cult to remove. V

Moreover, the boron compounds incorporated in liquid-leaded motor fuelsare volatilizable under the combustionzone conditions, and also exist inthe vapor sis phase in the combustion zone. If such organic boron 2compounds were present in the oil, they would, under the combustion zoneconditions, nonetheless be expected to volatilize. Compounds having amuch higher boiling point are necessary for use in lubricating oils.Such compounds should also be stable in the presence of moisture.Because of this, it has not been possible to incorporate these compoundsin the oil.

It has now been determined, in accordance with the invention, that thereaction products of boric acid with certain highly branched :x-alkyleneglycols in the proportion of two moles boric acid to three moles of thea-alkylene glycol are oil-soluble, more moisture-stable, and have lowvolatility, provided the glycol has at least eight carbon atoms up toabout twenty carbon atoms. Engines operated with lubricating oilscontaining such boron compounds have improved performance. The depositsare reduced. The ignition temperature of such engine deposits as remainis increased, therefore repressing surface ignition. It is thought thatthe boron compounds react with the lead in the deposits forming leadborate, and that this does not act catalytically to the same extentbecause it has a higher glow point than the lead oxide and lead sulfateusually present in such deposits. These additives are compatible withconventional lubricating oil additives.

The reaction products in accordance with the invention are defined bythe following general formula:

Where R, R and R" are a-alkylene radicals having a straight or branchedchain of from eight to twenty, preferably from eight to ten, carbonatoms, a chain of three carbon atoms linking the radical to the group.R, R' and R" have the structure, and can be the same or different:

The free valences are attached to oxygen, as shown in I above, R R R andR are selected from the group consisting of hydrogen and alkyl, and havea sufiicient number of carbon atoms in the aggregate to total from sixto eighteen carbon atoms. At least three of R R R and R are alkyl, andthe other can be hydrogen or alkyl. When one of R R R and R is hydrogen,preferably the R attached to the CH is branched, preferably tertiary.The R R R and R radicals can be straight-chain or branched alkylradicals; preferably at least one of R R R and R is branched, preferablytertiary. Thus, R R R and R, can be methyl, ethyl, propyl, isopropyl,butyl, isobutyl, tertiary butyl, secondary butyl, amyl, isoamyl,neopentyl, hexyl, heptyl, octyl, nonyl, deeyl, undecyl, dodecyl,tridecyl, tetradecyl, pentadecyl, heptadecyl and octadecyl radicals,taken in sufficient number to meet the requirements of the formula larspecies are possible, the two borates of each glycol and four mixedborates.

K 0a; 7 on; oHr-o-om-oH-o on, o-oH,-o -on.

n, B-o-on-h-o-B Hi oH3-o--o H, lHa o-o-om Ha CHa-C-CH; JHa

complex mixtures of reaction products can be obtained from mixtures ofthree and more oc-diols. However, all

of these are operative in the compositions of the invention;

The borate compounds of the invention are solids or liquids which arestable to moisture. The liquids and the solutions of the compounds inoil remain homogeneous and clear when stored in a moisture-saturatedchamber for forty-eight hours at room temperature (25 0.). They aresoluble in petroleum lubricating oils at very large concentrations. Theyare substantially involatile at crankcase temperatures.

These compounds can be prepared by mixing the reactants in thestoichiometric 3:2 molar ratios and heating them above 60 C., up toabout C., on a steam plate or hot plate, 'with occasional stirring,until the theoretical amount of water is lost. The loss of water isdetermined by the weight loss of the reaction vessel and contents.Alternatively, the reactants can be refluxed in the stoichiometricratios in dry benzene in a flask provided with a water condenser and awater-collecting trap until the theoretical amount of Water has beenazeotropically distilled. This permits use of a lower temperature. Thewater removed is determined by the water in the trap. The benzene .thenis removed from the reaction mixture by distillation, and the residuevacuum-distilled or recrystallized.

The compounds numbered (1), (2) and (29) above were subjected toscreening tests to determine oil solubility, moisture stability andvolatility. Oil solubility was observed at a concentration of about 0.1%boron. Moisture stability was studied with both the undiluted liquidadditive and an oil solution containing at least the equivalent of 0.1%boron. Samples had to remain visually unchanged with respect tohomogeneity and clearness after being stored in a moisture-saturatedchamber for fortyeight hours. Volatility was determined by thedistillation The borate compounds of the invention can be used with anypetroleum hydrocarbon oil of lubricating viscosity. The SAE viscositiesfor lubricating oils range from N0. 10 to No. 70. The neutral oils andrefined .oils,;-suc h as the acid-treated and solvent-extracted oils,

are equally useful in the compositions of the invention. The oils may beblended from suitable bright stocks and finished neutral or refined oilsof light and heavy viscosities. It is impossible here to give a completedescription of the various methods used in the preparation oflubricating oils, but reference is made to the text by Georgi entitledMotor Oils and Engine Lubrication, published by Reinhold PublishingCorporation, New York (1950),

7 chapter V, wherein the various types of lubricating oils are discussedfully. Any of the oils mentionedtherein can be employed in thecompositions of the invention.

Relatively large amounts of the organic borate compounds of theinvention, in oils as compared to the amounts required in gasoline, areneeded to give an improvement in engine performance. All proportions ofthe compounds are based on the amount of boron in the compound as apercent of the total oil composition, since it is the boron that is theactive component in removing the deposit. At least 0.05% is the minimum.Use of amounts in excess of 0.5% usually cannot be justifiedeconomically, and excessive amounts may lower the viscosity index.

The composition of the invention is prepared simply by mixing the boroncompound with the oil at room temperature. The boron compound is solublein the oil, and dissolves therein either instantaneously or after ashort time. No solvents are required.

The following examples represent in the opinion of the inventors thebest embodiments of their invention.

Examples 1 to 3 Three lubricating oil compositions were prepared using alubricating oil blend of 67% solvent-extracted neutral oil, 300 SSU at100 F. and 33% of a solvent-extracted bright stock, 78 SSU at 210 F. tothe oil was added 2% of the following borate compounds:

When the above oils were used in the crankcase of an internal combustionengine operating for a period of over seventy-two hours onnonboron-containing gasoline and the engine was then dismantled, thedeposits in the combustion chamber were found to contain boron with theattendant advantages of the same in the deposit as discussed earlier.

The compositions were subject of the Falex E.P. test, run by thestandard procedure, where the load on the hearing was increasedautomatically and the pressure reported was that registered at failure.The wear tests were run on the same equipment using a constant pressureon the bearing.

The data showed that the oil of the invention containing the boroncompound tolerated higher pressure and '8 produced less wear than eitherthe corresponding blend without boron or the base oil alone, therebyindicating that there would be no adverse etfect by their use incrankcases of engines.

We claim:

1. Petroleum lubricating oil having dissolved therein a moisture-stableorganic boron compound having the formula:

where R, R and R" are a-alkylene group having from eight to twentycarbon atoms having the structure:

R1 R4 the free valences being attached to oxygen, and R R R and R beingselected from the group consisting of hydrogen and alkyl, at least threeof R R R and R being alkyl, and the remaining R being selected from thegroup consisting of hydrogen and alkyl, the amount of said compoundbased on the Weight of the lubricating oil being equivalent to from 0.1to 0.5% by weight of boron.

2. Lubricating oil in accordance with claim 1 in which the boroncompound is:

3. Lubricating oil in accordance with claim 1 in which the boroncompound is:

4. Lubricating oil in accordance with claim 1 in which the boroncompound is:

References Cited in the file of this patent UNITED STATES PATENTS CHB0-C----C----0B CHCH -C--O CH CH O- -CHCH CH I CH CH CH f --J coIumu '3,line 61, ion "of" read to column S line 13 Zor "group" reed groupsSigned and sealed this 28th day oi November 1961:.

(SEAL) Attest: ERNEST W. SWIDER DAVID L. LADD Commissioner of PatentsUNITED STATES PATENT OFFICE CERTIFICATION OF CORRECTION June 20 1961Patent No. Z QBQ IGY Samuel M. Darling et al3 in the above numberedpattified that error appears ers Patent should read as It is hereby cerion and that the said Lett ent requiring correct corrected below.

lug"

Column 1, line I8, "for "sperkp lines 70 to 75, compound (19) shcuIcIreed sgserkplugs as shown column I, below instead 01"- es in the patent:

BO-C- ---C---O-B CH 3 C H C-O CH CH O--C-CH -=CH CH CH CH Times I too,compound (20) should appear as shown 6 oi as in the patent:

column 5,

heIe-w iustee O-CHtert-C H Attesting Officer

1. PETROLEUM LUBRICATING OIL HAVING DISSOLVED THEREIN A MOISTURE-STABLEORGANIC BORON COMPOUND HAVING THE FORMULA: